Recent progress in the field of microelectronics has led to the development of systems for producing fine or even ultra-fine wafers, the thickness of which is typically between 20 and 200 microns. Several techniques have been developed for the processing and handling of these fine wafers, in particular by temporary adhesive bonding methods. More precisely, the technique of temporary adhesive bonding makes it possible to manipulate and perform technological steps on a fine wafer supported by a so-called “support” or “handle” wafer, for example made from glass or silicon, which remains thicker. It is a question of temporarily bonding the fine wafer on which technological steps are to be performed on a “support” wafer, providing the mechanical rigidity for the whole. When all the steps have ended, the fine wafer will be detached from the “support” wafer. The thinning, to obtain the fine wafer, may also take place after bonding to a support substrate, the wafer thus thinned then being able or not to undergo additional technological steps with a view to producing all or some of the electronic and/or optical and/or mechanical components. In many temporary adhesive bonding techniques, the detachment takes place with a concatenation of chemical and mechanical actions.
The document US 2014/0084423 describes a method for the temporary adhesive bonding of a thinned wafer on a “support” wafer. The method further comprises a step of trimming the peripheral region of the thinned wafer. This step of cutting the edges of the previously thinned wafer then supported by the “support” wafer is performed by means of a diamond wheel. This trimming step is normally carried out by a mechanical means. It may thus cause a posteriori damage on the thinned wafer. The cutting step is followed by a step of joining the thinned wafer from the “support” wafer. This series of steps has limitations for fine wafers. This is because, where the wafer obtained after the disjoining step is particularly fine (extending from a thickness of less than 200 microns for example), no solution allowing manipulation without risk of breaking the thinned wafer is envisaged. In this case, no method can consequently be envisaged after disjoining; a method of cutting the thinned wafer chip by chip will for example be unachievable. Where the thinned wafer obtained after the disjoining step has a high mechanical stress, there are also high chances that the thinned wafer may a posteriori undergo deformation in a tile shape, which there also makes it tricky to handle the thinned and very probably weakened wafer during the continuation of the production method. Thus the method proposed in the document US 2014/0084423, because of the weakening of the thinned wafer that it causes following the mechanical stresses produced on said wafer, is difficult to implement industrially.
The present invention makes it possible to solve all or at least some of the drawbacks of the current techniques by proposing an alternative production method compatible with use in industry.